A conventional door window lifting apparatus of a vehicle includes a holder positioned beneath a door window and a guider, with a guide groove, horizontally welded beneath the holder. Typically a regulator arm moves along the guide groove to operate the window either up or down. Often a roller is rotatably installed between the regulator arm and the guide groove to reduce friction associated with rolling up or down the window.
However, there is a drawback in the conventional door window lifting apparatus in that an irregular sound is generated when the window is rolled up or down. The noise occurs because the roller gradually wears out due to the repeated sliding motion of raising and lowering the window.